Today light emitting elements that are mounted on a substrate, such as light emitting diodes (LEDs) mounted on a printed circuit board (PCB), are increasingly used in illumination devices. To generate a desired beam shape, such an LED-based illumination device may often comprise an optical system with an optical element, such as a collimator, arranged for each of the LEDs. As an example thereof, a known illumination device 100, where an optical system 101 with multiple collimators 102 is arranged over a plurality of LEDs 103 mounted on a PCB 104, is schematically illustrated in FIG. 1.
To optimize the performance of the optical system in FIG. 1, each of the LEDs must be aligned to its respective collimator. This can be done by adjusting the collimator, or, if each LED is mounted on a separate printed circuit board (PCB), by adjusting the position of the printed circuit board on which the LED is arranged. However, to facilitate assembly and/or exchangeability of the LEDs, it is often preferred to use one printed circuit board with multiple LEDs arranged thereon. Therefore, after the LEDs have been mounted on the printed circuit board, the LEDs have fixed position relative to each other. This means the only alignment that is left in the optical system is the adjustment of the collimators, which can be a very inconvenient and time spending process in production.
Thus, there is a need to facilitate the alignment of light emitting elements to their respective optical elements, even though the light emitting elements are mounted on the same substrate.